Generation of atom-atom correlations inside and outside the mutual light cone

We analyze whether a pair of neutral two level atoms can become entangled in a finite time while they remain causally disconnected. The interaction with the e. m. field is treated perturbatively in the electric dipole approximation. We start from an initial vacuum state and obtain the final atomic correlations for the cases where n = 0, 1, or 2 photons are produced in a time t, and also when the final field state is unknown. Our results show that correlations are sizable inside and outside the mutual light cone for n= 1 and 2, and also that quantum correlations become classical by tracing over the field state. For n = 0 we obtain entanglement generation by photon propagation between the atoms, the correlations come from the indistinguishability of the source for n = 1, and may give rise to entanglement swapping for n = 2.Comment: v2: Minor changes, references added. v3: full revision, appendix added. v4: Minor changes. Accepted in Phys. Rev.

RWOPS abuse could cost, or even ruin, offenders

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Capacitors can radiate - some consequences of the two-capacitor problem with radiation

We fill a gap in the arguments of Boykin et al [American Journal of Physics, Vol 70 No. 4, pp 415-420 (2002)] by not invoking an electric current loop (i.e. magnetic dipole model) to account for the radiation energy loss, since an obvious corollary of their results is that the capacitors should radiate directly even if the connecting wires are shrunk to zero length. That this is so is shown here by a direct derivation of capacitor radiation using an oscillating electric dipole radiator model for the capacitors as well as the alternative less widely known magnetic 'charge' current loop representation for an electric dipole [see for example "Electromagnetic Waves" by S.A.Schlekunoff, van Nostrand (1948)]. Implications for Electromagnetic Compliance (EMC) issues as well as novel antenna designs further motivate the purpose of this paper.Comment: 5 Pages with No figure

RWOPS abuse ‘eroding ethical standards of juniors’

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Doctors’ lifestyles vital for SA’s health – global expert

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Much ado over the new South African PMTCT guidelines

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Inspanning all the oxen – new Health Foundation

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The Impact of Victor Hugo’s Writings from Exile upon the French Second Empire

When Louis-Napoleon staged a coup d’état and overthrew the French Second Republic in 1851, renowned French author and republican politician Victor Hugo escaped into exile on the British isle of Guernsey. He remained in exile until the republic was reestablished in 1870. This thesis examines the works he published during the period, including the political pamphlet Napoléon le Petit, two poetry collections—Les Chȃtiments and Les Contemplations—and his magnum opus novel Les Misérables. Victor Hugo used these writings to remain politically active, even while in exile, by consistently promoting the cause of republicanism in France. His politically charged writings helped shape the course of French politics in the 1860s, ultimately contributing to the fall of the French Second Empire and the restoration of the Republic